1. Field of Invention
The present invention relates to land transportation vehicles and particularly to a fiber reinforced plastic composite vehicle chassis. More specifically, it relates to a one piece vehicle chassis that has particular usefulness in smaller vehicles such as lawn and garden tractors, golf carts and utility vehicles.
2. Description of the Related Art
Reinforced polymer composites have been utilized in vehicles for some time. They have been used for auto shells which have been fastened to metal frame structures, for undercarriage parts fastened to metal frames and for body panels fastened to metal frames. Each of these applications depended upon the metal frames to resist torsional and bending loads encountered by the vehicles.
Recently, fiberglass reinforced plastic composites have been used to produce a vehicle assembly which did not require the use of metal frame members. Utilized in that application were thermoplastic composites, which facilitated the use of injection molding processes and therefore permitted the use of mass production applications for this chassis. As a result of using thermoplastic materials, which are less resistant to fatigue and creep than thermoset polymers, the vehicle chassis was composed of three separate parts, that when assembled formed hollow compartments. The walls of these compartments then provided the frame-like strength necessary to withstand the concentrated torsional and bending loads previously resisted by metal frame members. This assembly not only required three members, but depended upon them being satisfactorily bonded together to assure integrity of the compartments that resisted the torsional and bending loads.
While frame-like sturdiness and rigidity has been achieved in plastic chassis through use of the three part monocoque structure mentioned above, it would be desirable to provide a single piece plastic vehicle chassis that could resist torsional and bending forces while providing those frame-like characteristics.
It would also be desirable to provide a reinforced plastic composite chassis capable of supporting an engine, an operator, drive and steering wheels, and steering system, and which would be capable of flexing throughout its length and width to absorb torsional and bending loads encountered during operation.
Additionally, it would be desirable to provide a single piece composite chassis which could resist such loadings and also serve as a suspension stem to accommodate ground irregularities and variations. With such a chassis, there would be no need to rely upon bonded joints for resisting bending and torsional loadings. Further, it would be desirable to provide a suspension system which could be used to support a portion of the chassis, such as an operator station on the chassis base.
It would also be desirable to provide a single piece chassis that could be mass-produced not only by injection molding techniques but by compression molding, liquid composite molding techniques or by hand lay-up. Additionally, it would be desirable to be able to produce the single part plastic chassis with thermoplastic or thermoset polymers that would make available the broadest design capabilities and greater opportunity for cost effectiveness.